Bacterial Infections or Viruses

Many common illnesses fall into two broad categories: bacterial and viral. This guide will help explain the difference between bacterial and viral infections, know what to expect at the doctor’s office, and feel more confident about what to do next. If you’re also looking for ways to comfort your little one when they’re under the weather, check out the Nestlé FamilyNes article on Toddler Health Concerns – Looking After a Sick Toddler. The information in this article is general in nature and should not replace medical advice from your own doctor.  

What are bacterial and viral infections?

Understanding what bacterial infections or viruses are and what causes them can help guide the right treatment.

What are bacteria?

Bacteria are single-celled living organisms. Many bacteria are harmless or even helpful, such as the ones that help with digestion in our gut. However, some can cause illness when they multiply and overwhelm the body’s defences.

Examples of bacterial infections in babies include:

• Ear infection (otitis media)
• Urinary tract infection (UTI)
• Bacterial pneumonia
• Strep throat (less common in infants but possible)

Because bacteria are living, antibiotics can kill them or stop them from growing.

For more about one common bacterial infection, see From Symptoms to Solutions: Navigating Infant Ear Infections.

What are viruses?

Viruses are much smaller than bacteria and are not technically alive because they need to invade healthy cells to reproduce. The immune system usually clears viruses on its own, and antibiotics do not work against them.

Examples of viral infections in babies include:

• Common cold
• Influenza (flu)
• Respiratory syncytial virus (RSV)
• Viral gastroenteritis (tummy bug)
• Roseola

If your baby has a fever with a bacterial or viral illness, see the Nestle FamilyNes article on Understanding Baby Fever: Tips for Comforting Your Little One.

What are the differences between bacterial and viral infections?

While both cause illness, they have some core differences that can help parents understand how they behave:

• Bacteria are living organisms that can grow and multiply on their own.
• Viruses are not alive; they must infect a host cell to replicate.
• Antibiotics treat bacterial infections but not viral ones.
• Viral illnesses are more common in young children, especially colds and mild fevers
• Bacterial infections are less common but may be more severe or localised (like an ear or urinary infection)
• It is possible for a child to have both viral and bacterial infections one after the other or even at the same time

This distinction between bacterial and viral infections matters because the right treatment depends on the cause. Viral infections usually need supportive and symptomatic care, while bacterial infections are likely to need antibiotics.

Symptoms of bacterial infections and viral infections in your little one

It can be tricky to tell the difference just by looking since symptoms for both bacterial and viral infections often overlap. However, there are some general patterns:

Symptoms of bacterial infection

• Sudden onset of symptoms
• Localised impact (for example ear, throat, chest, or urinary area)
• Redness, swelling, or pus
• Fever that may be high and persistent
• Symptoms get worse instead of better over a few days
• Child may seem very unwell or unusually irritable

Viral infection symptoms

• Gradual onset of symptoms
• Often affects multiple symptoms
• Runny or congested nose
• Sneezing, coughing, watery eyes
• Mild to moderate fever
• Fatigue, fussiness, or body aches
• Symptoms usually improve on their own after a few days

Because symptoms of bacterial infection and viral infections can overlap, it’s best not to self-diagnose. If you have any concerns, seek professional medical advice to help evaluate and confirm the cause and ensure your baby gets the appropriate care.

How are these infections diagnosed?

If your baby seems unwell, your GP or paediatrician will usually:

• Ask about your child’s symptoms, when they started, and how they’ve changed
• Do a physical exam (looking at the ears, throat, chest, tummy, and skin, body temperature)
• In some cases, order tests like throat swabs, urine tests, or blood tests to aid in diagnosis

Key points to know:

• Not all illnesses need tests since mild viral infections usually clear on their own without any medication or antibiotics
• If symptoms are more severe or not improving, tests help to rule out a bacterial infection.
• It’s normal for doctors to wait and watch if symptoms are mild and are likely to be a viral infection.

Seek medical help promptly if your baby has:

• Persistent fever (especially in babies under 3 months)
• Breathing difficulties (fast, noisy, or laboured breathing)
• Poor feeding or signs of dehydration (dry nappies, sunken soft spot)
• Unusual drowsiness, limpness, or unresponsiveness

Trust your instincts. If you’re worried, it’s always safest to get your child reviewed by a doctor.

Bacterial infection and virus treatment for little ones

Most common infections in babies can be managed safely at home with guidance from a healthcare professional. Staying calm and following your doctor’s advice helps your baby recover comfortably.

Bacterial infections treatment

If your baby has a confirmed bacterial infection, your doctor may prescribe antibiotics. Examples include middle ear infections, some chest infections, or urinary infections.

Important reminders for parents:

• Always follow the prescribed dose and timing.
• Complete the full course, even if your baby seems to be improving. This helps to prevent antibiotic resistance from developing.
• Only use antibiotics if prescribed specifically for your baby’s current illness
• Never share leftover antibiotics or start them without medical advice. Using them incorrectly can make bacteria develop resistance to antibiotics and harder to treat.

Viral infections treatment

Viral illnesses, like colds, influenza, or Respiratory syncytial virus (RSV), cannot be treated with antibiotics. Instead, focus on comfort and supportive care for your child:

• Keep your baby hydrated (offer regular breastfeeds or formula).
• Make sure they get plenty of rest.
• Use saline drops and a gentle suction bulb for blocked noses.
• Offer infant-safe fever relief (like Paracetamol or Ibuprofen) if advised by your doctor.

Most viral infections will clear on their own with time and rest.

Preventing infections in babies

While it’s impossible to avoid every germ, small daily habits can help protect your baby:

• Wash your hands before feeding, or handling bottles and dummies, and after changing nappies.
• Coughing or sneezing into your elbow.
• Not sharing cups or cutlery.
• Regularly sterilise feeding equipment and clean toys and surfaces.
• Keep sick visitors (even mildly unwell) away from newborns.
• Wear a mask if you have a respiratory illness to reduce potential droplet spread to your child.
• Stay on top of your baby’s vaccinations, which are a safe and important way to prevent serious illnesses while their immune system is still developing.

These steps reduce the chance of your baby catching infections and can help make it easier for them to fight off bugs if they do get sick.

Final thoughts on infections in babies

Bacterial and viral infections are common in infancy and most can be safely managed at home with supportive care and guidance from a healthcare professional.

Good hygiene, balanced nutrition, and timely vaccinations are key to helping your little one stay healthy during their early, more vulnerable months.

And most importantly, trust yourself. If you’re unsure about your baby’s symptoms or next steps, it’s always okay to ask your doctor for advice.

By staying informed, spotting warning signs early, and following simple daily routines, you’re already doing a great job protecting your baby’s health.